Needing help with 9mm AR15.
I’ll try to cut to the chase. I have a customers AR15 in 9mm conversion that he knows squat about and brought it to me saying it was running auto (but not runaway). At the moment I can’t go test fire it at the gun club I belong too, but these issues are usually straight forward, except for this time. I check the obvious first. All parts are brand new, springs in correctly, disconnector working properly, sear looks good, etc. I would pull the charging handle, pull trigger, let the handle fly, yada yada. Nothing. This is a new build but I can’t find a name or number on anything except the Anderson lower. I even thought maybe it was slam firing but the firing pin is free and clean and the hammer can’t strip a round out of the mag and ride the bolt home either because the sear catches well before that. The bolt is ramped and the hammer is your standard AR hammer. I even weighed the buffer at 8ounces and the bolt at 12.5 and that seems about right. I just can’t find a reason that this thing would run auto AT ALL. Any recommendations or suggestions will be greatly appreciated. Also don’t have much experience with an AR in a blowback configuration.